The present invention relates to a change speed transmission for an automatic transmission of a vehicle, and more particularly to a compact arrangement of clutches and brakes.
The present invention aims at improving a change speed transmission such that its axial dimension is reduced.
A THM 700-4R type automatic transmission manufactured by U.S. General Motors is known. As shown in a publication "AUTOMOTIVE ENGINEERING" Vol. 36, No. 6, 1982 issued in 1982 by Japanese Automotive Engineering Society, this known automatic transmission can provide four forward speed ratios and a reverse speed ratio and uses two planetary gear sets. The planetary gear sets are selectively controlled by clutches and brakes which comprise a forward clutch, an input one-way clutch, a low one-way clutch, and a low & reverse clutch (which may be called as a low & reverse brake). When the forward clutch is engaged, first forward speed ratio is established. If engine braking is required under this condition, both the overrun clutch and low & reverse clutch are engaged to hinder the action of the input one-way clutch and low one-way clutch thereby provide engine braking at the first speed ratio.
In this change speed transmission, the forward clutch and the overrun clutch are disposed in tandem without any space-saving idea. Besides, the low & reverse brake and the forward clutch are arranged in tandem. This known arrangement results in an increased axial dimension of a change speed transmission.
An object of the present invention is to provide a compact change speed transmission wherein clutch and brake means are arranged in a space-saving manner as to contribute to a reduction of an axial dimension of the change speed transmission.